Immunoglobulin G (IgG) Subclass 1 and 2 Quantification in Serum

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms of a weakened immune system, such as frequent infections, recurrent ear or sinus infections, or if you’re at higher risk for infections due to conditions like HIV, chemotherapy, or certain autoimmune diseases. It may also be used to monitor treatment responses in conditions affecting immune function.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm to draw blood. It usually takes a few minutes, and you may feel a brief pinch. If you’re on blood thinners, let your provider know before the test.

What the Test Results Mean

IgG subclasses (IgG1 and IgG2) are measured in grams per liter (g/L) or milligrams per deciliter (mg/dL). Lower than expected levels in one or both subclasses may indicate immune system issues, while higher levels could be due to certain medical conditions or treatments. Your results will be compared to standard reference ranges provided by your lab.

Common Conditions Monitored or Diagnosed

IgG subclass testing helps diagnose or monitor conditions such as common variable immunodeficiency (CVID), autoimmune diseases, or infections. It can also assess how well certain treatments (like IVIG therapy) are working to boost immune function.